It is a known procedure to cultivate plants in greenhouses. Glass, especially silicate glass or horticultural cast glass, for example, is used for the glazing of these greenhouses.
Preference is usually given to the use of horticultural cast glass since, thanks to its structure, it protects the plants from being burned by direct sunlight and provides diffused light for the plant culture.
The insulation of greenhouses glazed in this manner, however, is usually inadequate. As a result, a great deal of energy is needed to cool these greenhouses in the summer and in turn, a great deal of energy is also needed to heat these greenhouses in the winter.
The use of insulating glass for the glazing of greenhouses is not very widespread since the light transmittance of insulating glass is about 10% less than that of single glass. As a result, a lower yield is expected.
In this context, the transmittance of the greenhouse or of the glazing employed plays an important role over the entire wavelength range, since 1% more transmittance usually translates into a 1% greater yield of the plant culture.
However, glass-like polymer materials are now also being used more and more often for the glazing of greenhouses.
These materials have the advantage that, in comparison to glass, they are lightweight, unbreakable and are usually produced in the form of sandwich panels, hollow chamber panes or else as so-called double skin sheets or even triple skin sheets.
However, these materials also have considerable drawbacks since they can, at times, be transparent to UV light, thus contributing to burning of the plant cultures when the light radiation is strong. Moreover, these materials are not very UV-stable and they age when exposed to constant light radiation. Moreover, the insulation of sandwich panels, hollow chamber panes or so-called double skin sheets or even triple skin sheets is inefficient in comparison to insulating glass.
In view of these advantages and disadvantages of the various materials used for glazing, it can be difficult to attain optimal conditions that are adapted to the specific cultivated plants for a given plant culture.